Many of us seek out sunny, warm climates, saunas, steam baths, hot tubs, and solariumespecially during winter months. Few of us show the same enthusiasm for stripping down for a skinny dip in a frozen lake or for a mid-winter vacation spent sitting outside freezing in a bikini. We don't like the darkness or the cold.

Yet most research with respect to heat ignores our love of hot spots. Instead the search focuses on the damaging effects of extreme heat exposure.

Titles like "Hyperthermia and dehydration in marathon runners" or "The health risks of hot tubs" abound. One of the few areas in which the potential health benefits of heat have been studied is in the sauna.

Heat helps

Why would people subject themselves to heat stress? Many people find saunas pleasurable, relaxing, and believe that saunas are good for health. The heat of the sauna helps relax tense muscles; electrical discharges in muscles show a more relaxed pattern following a sauna.

A brief trip to the sauna decreases pain in muscles and joints. An intriguing study in Czechoslovakia demonstrated that sitting in a sauna for 30 minutes doubled beta-endorphins levels in the blood. Recall that endorphins are internally produced chemicals which relieve pain and may also produce a sense of well-being and euphoria. So it may not be so far-fetched to speak of a "sauna-bathers high."

The relaxation following a sauna may also be due to other chemical changes in the brain. The heat may deplete our body stores of stress hormones. This makes us less likely later to respond to stressa beneficial type of "burnout." Saunas also increase serotonin, a powerful hormone associated with relaxation and sleep. Following a sauna, people show more brain waves related to deeper, more restful sleep. So a sauna or hot bath may be an excellent way to relax before sleep.

Cook that cold

Many sauna bathers claim that a sauna helps ward off colds and other infections. They may well be right. Children who regularly take saunas have better resistance to infection. Forty-four kindergarten children in Germany were divided into two groups with half the children partaking in a weekly sauna. Over the following 18 months the number of sick days due to colds, ear infections, and associated maladies for each group was tallied. The children taking the regular sauna bath had only half the number of sick days compared to the cooler control group.

The high temperatures produced by the sauna may simply cook and kill the germs. Or the elevated body temperatures may simulate the beneficial effects of a fever. There is growing evidence that a fever may actually help the body resist and fight infections. When the body is infected, pyrogens, chemicals that turn up the body's thermostat, flood the bloodstream and bolster the immune system. The invading germs are simultaneously attacked and starved of vital nutrients.

This rise in temperature appears to be healthful: when experimental animals are prevented from raising their body temperature in response to an infection, the death rate increases. A sauna may be a more pleasurable way to produce an artificial fever and more functional; wouldn't you rather lie back in the heat once in a while, killing germs, than be forced to lie back for week or so killing the germ with a fever?

Sweat the pounds

Sauna bathing may even be a pleasant adjunct to physical exercise for burning calories and conditioning the heart. Sweating is an active physiological response to help lower body temperature. It involves the expenditure of a considerable number of calories; a person can burn up 300 to 800 calories during a sauna. Sauna bathing, like physical exercise, also places a stress on the heart and may to some degree improve conditioning.

Warm pleasures

The healthy pleasures of sauna bathing and hot baths may go well beyond these beneficial physiological measures. A dip in the heat is a great excuse for a protected, quiet rest period in an otherwise harried lifestyle. Again, we need return to our origins: remember that human beings evolved as a tropical animal, well adapted to the warmer temperatures of the African savannah.

For many northerns, separated by thousands of miles and many degrees from the tropical climates of our ancestors, a sauna or hot bath may provide a brief respite, a reminder of warm times and warm pleasures.